Tai Kwondo is great for discipline and just keeping a kid active. It will teach him manners and give him confidence. There is a lot of sparring involved so he will learn some good fihting skills. What it will not do is turn him intoa great fighter. That comes from mixed martial arts and a lot more aggressive discipline than taikwondo. My son is a Level II Black Belt in Tai Kwondo and had belts in jui jitsu and Han Mu Do (sp??). He has won multiple World Championships in sparring, Tradition Forms, and Free Style Forms. PM me and I can tell you more about it. It was really good for him bu like everything else, it grew tiresome after sveral years. He is a very well manner young man and will "yes sir/no sir" you to death.
PS. He's only 13 so I can still kick his little ***.